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Bison

Bison congregate during the breeding season to compete for mates. This has enabled the successful restoration of a population that was on the brink of extinction just over a century ago.

NPS / Jim Peaco

Yellowstone is the only place in the United States where bison (Bison bison) have lived continuously since prehistoric times. Yellowstone bison are exceptional because they comprise the nation’s largest bison population on public land and are among the few bison herds that have not been hybridized through interbreeding with cattle. Unlike most other herds, this population has thousands of individuals that are allowed to roam relatively freely over the expansive landscape of Yellowstone National Park and some nearby areas of Montana. They also exhibit wild behavior like their ancient ancestors, congregating during the breeding season to compete for mates, as well as migration and exploration that result in the use of new habitat areas. These behaviors have enabled the successful restoration of a population that was on the brink of extinction just over a century ago.

However, some Yellowstone bison are infected with brucellosis, a livestock disease that can be transmitted to wild bison and elk as well as cattle through contact with infected fetal tissue. To prevent conflicts with ranching and other activities outside the park, the National Park Service works with other federal, state, and tribal agencies to manage and develop policies for bison access to winter range outside the boundaries. Conservation of wild bison is one of the most heated and complex of Yellowstone’s resource issues. All of the interested parties bring their own wide-ranging values and objectives to the debate. Continue: Description, Migration, and Habitat

Quick Facts

Number in Yellowstone

Estimated at 5,500 in August 2016. This includes two sub-populations in Yellowstone: northern (3,152 to 4,042 animals) and central (1,451 to 1,639 animals).